Analyzing hydrocarbon fluids provides insight into hydrocarbon fluid reservoir potential. Data from the analysis can be useful in understanding the quality and economic value of produced fluids from the reservoir. In some applications, the composition of water produced or injected is analyzed to improve controls in flow assurance. The produced or injected water may contain a variety of organic and inorganic anions and cations that may be subjected to the analysis. The fluids may be analyzed at the wellhead or in a laboratory, although the results of surface-based analyses may vary in accuracy because conditions at the surface may be different from conditions at the subterranean location.